Manufacture of artificial materials



Jan. 3, 1939. R. w. MONCRIEFF ET AL 2,142,911

MANUFACTURE OF ARTIFICIAL MATERIALS Filed July 23, 1937 Patented Jan. 3,1939 PATENT OFFICE 2,142,911 MANUFACTURE OF ARTIFICIAL MATERIALS RobertWighton Moncriefl and Frank Brentnall Hill, Spondon, near Derby,England, assignors to Celanese Corporation of America, a corporation ofDelaware Application July 23, 1937, Serial No. 155,192 In Great BritainJuly 30, 1936 Claims.

This invention relates to improvements in the manufacture of artificialmaterials, and particularly to improvements in processes for stretchingartificial filaments and other products hav- 6 ing a basis of celluloseacetate or other organic derivative of cellulose.

In U. S. application S. No. 17,242, filed April 19, 1935, processes aredescribed for the stretching of artificial filaments, foils and similarmaterials in which the materials are passed in substantiallynon-slipping contact with'a positively driven feed device contained inan end chamber which contains a compressed inert fluid, and from thischamber into a pressure treatment chamber communicating therewith, whichcontains hot water and in which they are stretched. The specificationalso describes and claims apparatus for carrying out this process. Bymeans of the 'end chamber flow of hot water through the inlet passagesfor the materials into the treatment chamber may be reduced oreliminated. The materials may issue from the treatment chamber directlyinto the outer air, or they may pass from the treatment chamber into asecond end chamber containing a compressed inert fluid and having asimilar function and thence into the outer air.

It has now been discovered that particularly good results may beobtained by the use of cold, or relatively cold, water as the inertfluid present in the end chamber or chambers. The water may be atatmospheric temperature or below or at a temperature above atmospherictemperature, for example a temperature of 25 or 35 C. or even more, butthe temperature must not be so high that softening and stretching of thematerials takes place in the end chamber or chambers themselves. Thepressure of the water in the end chamber or chambers may be equal to orgreater or less than that of the water in the stretching chamber, but ispreferably substantially the same. For example, the pressure of thewater in the end chamber may be slightly lower than the pressure in thetreatment cham- 45 her, e. g., of the order of 1 to 5 pounds per squareinch lower.

For details with regard to the stretching conditions and the apparatuswhich may be employed reference is made to U. S. application S. No.17,242. Stretching may be effected in hot water at a temperature of, forexample, 110 0., 125 C., 140' C. or more, and at a pressurecorresponding with the vapour pressure of water at the temperatureemployed. The materials may be stretched to a relatively low degree, forexample,

150, 200 or 300% of their original length, or to a considerably greaterextent, for example to 1000% or more of their original length. As statedabove either a single end chamber containing a feed device for thematerials and situated at the inlet end of the stretching chamber may beemployed, or end chambers at both ends of the stretching chamber may beemployed, in which case the chamber at the outlet end may contain thestretching device.

The water in the stretching chamber may contain solvents or plasticizerspreferably in low concentrations, e. g., concentrations of 1-5 or 10%.Examples of suitable substances are methyl and ethyl alcohols, dlbutyltartrate, diethyl lactate, aromatic sulphonamides, e. g., tolueneparasulphonamide and benzyl alcohol. Examples of other substances whichmay be employed are given in U. S. Patent No. 2,072,251.

The accompanying drawing illustrates, more or less-diagrammatically, anapparatus which may be employed in carrying out the process of thepresent invention.

The apparatus comprises an end chamber 4 connected with a pressuretreatment chamber 1 by means of small orifices 6 for the passage of thematerials. The chamber 4 is provided with an inlet II and an outlet l3by means of which water may be passed through the chamber. Itis alsoprovided with inlet orifices 3 for the materials, apressure gauge 12 anda positively driven feed device 5. The pressure treatment chamber 1comprises an inlet pipe l5 and outlet pipe l8 by means of which hotwater may be passed through the chamber, a heating coil H, a pressuregauge i4 and a valve controlled drain l8. It is also provided withoutlet orifices 8 for the materials.

In carrying out the stretching process according to the presentinvention using apparatus such as that illustrated in the drawing anumber of filaments 1 taken from a creel of bobbins 2 may be passedthrough the inlet orifices 3 into the end chamber 4 which contains coldwater under pressure. After entering the chamber they pass in contactwith the positively driven feed device 5, and then through the orifices6 into the treatment chamber I where they are stretched during theirpassage through hot water by means of the positively driven feed devices9 positioned outside the chamber. From these devices they pass to acreel of take-up bobbins Ill.

The following example illustrates the invention, but is not to beregarded as limiting it in any way.

Example Cellutose acetate yarn is passed through end chamber in contactwith a positively driven feed device and then through a stretchingchamber communicating with the end chamber, the stretching chambercontaining hot water at a temperature of about 143 C., while cold waterat a temperature of about 20 C. is circulated through the end chamber.'I'he pressure oi the water in the end chamber is'about 5 pounds persquare inchdess than that of the water in the stretching chamber. nissuing from the stretching chamber the yarn passes in contact with astretching device which is rotated at a peripheral speed such that thematerials are stretched in the stretching chamber toabout 10 times theiroriginal length. In this manner products having a high tenacity and agood'extensibility may be obtained.

The materials after being stretched may be subjected to a shrinkingprocess and/or a saponification process carried out continuously withstretching. For example on emerging from the stretching apparatus theymay be shrunk by passage through a shrinking bath containing methylenedichloride or other suitable shrinking agent as described in U. S.Patent No. 2,658,422, and then, after drying if necessary, through asaponiiying bath containing sodium hydroxide, methylamine, ethylenediamine or other suitable saponii'ying agent wherein they are partiallyor wholly saponified. Z 1 N The process is particularly valuable for thestretching of filaments, threads, and other materials of cellul oseacetate but is also applicable to the stretching of materials made ofother organic derivatives of cellulose, e. g., cellulose:

propionate and "butyrate and ethyl and butyl cellulose e Havingdescribed our invention what we desire to secure by Letters Patent is: rV 1. Process for improving the properties of artificial filaments,threads and similar materials of cellulose acetate, which comprisesrunning the materials from the outer air into an end chamber, whichcommunicates with a pressure treatment chamber and contains water at atemperature below that at which it exerts any softening action on the;materials, in substantially nonslipping contact with a positively drivenfeed de- I vice in the end chamber, thence throughethe communicationbetween the end and treatment chambers into hot water, at a temperatureabove 100 C. and a pressure substantially the same as that of the water.in the end chamber, contained in the treatment chamber, and finally intothe outer air, the materials being stretched while in the hot water.

2. Process for improving the properties of artificial filaments, threadsand similar materials of cellulose acetate, which comprises running thematerials from the outer air into an end chamber, which communicateswith a pressure treatment chamber and contains water at a temperaturebelow 35 C., in substantially non-slipping contact with a positivelydriven feed device in the end chamber, thence through the communicationbetween the end and treatmentchambers into hot water, at a temperatureabove 100 C. and a pressure substantially the same as that of the waterin the end chamber, contained in the treatment chamber, and finally intothe outer air, the materials being stretched while in the hot water.

3. Process for improving the properties of artificial filaments, threadsand similar materials 0! cellulose acetate, which comprises running thematerials from the outer air into an end chamber, which communicateswith a pressure treatment chamber and contains water at a temperaturebelow that at'which it exerts'any softening action on the materials, insubstantially nonslipping contact with a positively driven feed devicein the; end chamber, thence through the communication between the endand treatment chambers into hot water, at a temperature above 120 C. anda pressure substantially the same as that of the water in the endchamber, contained in the treatment chamber, and finally into the outerair, the materials the hot water.

4. Process for improving the properties of artificial filaments, threadsand similar materials of cellulose acetate, which comprises running thematerials from the outer air into anend chamber, which communicates witha pressure treatment chamber and contains water at a temperature belowthat at'which it exerts any softening action on the materials, insubstantially non-slipping contact with: a positively driven feed devicein the end chamber, thence through the communication between the end andtreatment chambers into hot water contained in the treatment chamber ata temperature above 100 C. and under a pressure between 1 and '5 poundsper square inch greaterihan that of the water in the end cham-' ber andfinally into the outer air, the materials being stretched while in thehot water.

5. Process for improving the properties of artificial filaments, threadsand similar materials 01' cellulose acetate, which comprises running thematerials from the outer air into an end chamber, which communicateswith a pressure treatment chamber and contains water at a temperaturebelow that at which it exerts any softening action on the materials insubstantially non-slipping contact with a positively driven i'eed devicein the end chamber, thence throughjthe communication between the end andtreatment chambers into' hot water contained in the treatment chamber ata temperature above 120 C. and under a pressure between 1 and 5 poundsper square inch greater than that of the water in the end chamber andfinally into the outer air, the materials being stretched while in thehot water.

ROBERT WIGHTON MONCRIEFF. FRANK BRENINAIL HILL.

being stretched while in 7

